<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>案例-顶部导航</title>
    <style>
        * {
            box-sizing: border-box;
        }

        .div1 {

            display: flex;
            justify-content: space-between;
            background-color: rgb(255, 255, 255);
            padding: 20px;
            border-bottom: 4px solid rgb(47, 207, 252);
        }

        .div1 div {
            padding: 10px;
            border-radius: 5px;
            border: 3px solid transparent;
            padding-left: 15px;
            padding-right: 15px;
        }

        .div1 div:hover {
            border: 3px solid rgb(47, 207, 252);

        }

        .div3 {
            width: 100px;
            height: 100px;
            background-color: 1px solid rgb(47, 207, 252);
        }
    </style>
</head>

<body>
    <div class="div1">
        <div class="div2">首页</div>
        <div>热门项目</div>
        <div>专家见解</div>
        <div>联系我们</div>
    </div>
    <div class="div3"></div>
</body>

</html>